Abstract
Incipient fault diagnosis is closely related to insulation condition assessment. A great number of methods are available for condition monitoring and diagnosis of power transformer insulation systems, but only few of them can take direct measurements inside the transformer. Fiber optic sensors can be applied to incipient fault diagnosis. In particular, acoustic sensors have been developed for detection and location of partial discharges in oil-filled power transformers. We report the study of extrinsic and intrinsic fiber Fabry-Perot sensors that can be used to detect the acoustic waves that are generated by a partial discharge inside a power transformer. A comparative analysis is done to determine the best sensing head configuration and some methods to improve the parameter readout sensitivity are proposed. The sensing head behaviour when immersed in different fluids (air, water, and oil) is also investigated. (c) 2009 Society of Photo-Optical Instrumentation Engineers. [DOI: 10.1117/1.3080752]

Abstract
In the recent years the ever growing concern of policy makers with respect to natural hazards has led researchers and practitioners to seek more reliable, precise and time efficient techniques map zones prone to hazards. Mass movement is a hazard common to many mountainous areas around the world which can pose a serious threat to the population living within the area as well as to the structures, property, environment and crops. Several geophysical methods assume a relevant role in monitoring and surveying unstable slopes. Our aim was to show that seismic refraction can meet the demands of a time efficient and cost effective method to map this vulnerability. We performed a series if profiles with the aim of determining distribution of rock weathering thickness and velocity distribution within the vicinity of Canelas (NW Portugal). The results of each profile were analysed to give thickness of geotechnical soil as well as average values for both near surface and deeper part of each profile. The results were georeferenced in GIS and thus the estimation of the spatial distribution of the parameters allowed a means of observing some correlation with the previously mapped features of the area, namely the geology and topography.

Abstract
A novel variant of a multi-objective particle swarm optimization algorithm is reported. The proposed multi-objective particle swarm optimization algorithm is based on the maximin technique previously proposed for a multi-objective genetic algorithm. The technique is applied to optimize two types of problems: firth to a set of benchmark functions and second to the design of PID controllers regarding the classical design objectives of set-point tracking and output disturbance rejection.

Abstract
In this paper, we study the performance of OFDM signals in frequency-interleaved WDM radio-over-fiber (RoF) links with optical channel selection made by a uniform Fiber Bragg grating (FBG). The frequency-interleaved signals, transported over 10 km of standard single mode fiber, were transmitted in optical double-sideband (ODSB) format and filtered in optical single-sideband (OSSB) format. The simulations were being performed using the software VPI and the system performance was evaluated in terms of Error Vector Magnitude (EVM). The EVM is kept below 10% in the 100 and 400 Mbits/s for some optical power values and the system performance is limited by the dispersion in the FBG and nonlinearities in the optical modulator.

Abstract

Abstract
The versatile transceiver in study for the Super Large Hadron Collider (SLHC) will have to endure severe radiation and temperature conditions while providing a high speed digital communication link to cover the experiment requirements. For this, characterization and model analysis of the electro-optic components (in particular the semiconductor laser), is of utmost importance as it will enable the correct design and optimization of the transceiver. It will also enable the prediction of the impact on the link performance when the physical characteristics of the device are changed due to the environmental circumstances. A measurement methodology is presented that leads to the conception of a model implemented in Verilog-A, for designing a robust system capable of complying with the demanding requirements of the experiment. The theoretical model shows a good agreement with the experimental data. This model was created based on a Vertical Cavity Surface Emitting Laser (VCSEL), but can be applied to a variety of lasers.